Install OGLCompiler et.al. even when building shared libraries.  Also fix
CMake file locations.

Patch taken from Gentoo:

  https://gitweb.gentoo.org/repo/gentoo.git/tree/dev-util/glslang/files/glslang-1.3.231-Install-static-libs.patch

diff --git a/OGLCompilersDLL/CMakeLists.txt b/OGLCompilersDLL/CMakeLists.txt
--- a/OGLCompilersDLL/CMakeLists.txt
+++ b/OGLCompilersDLL/CMakeLists.txt
@@ -41,7 +41,7 @@ if(WIN32)
     source_group("Source" FILES ${SOURCES})
 endif(WIN32)
 
-if(ENABLE_GLSLANG_INSTALL AND NOT BUILD_SHARED_LIBS)
+if(ENABLE_GLSLANG_INSTALL)
     install(TARGETS OGLCompiler EXPORT glslang-targets)
 
     # Backward compatibility
@@ -49,7 +49,7 @@ if(ENABLE_GLSLANG_INSTALL AND NOT BUILD_SHARED_LIBS)
         message(WARNING \"Using `OGLCompilerTargets.cmake` is deprecated: use `find_package(glslang)` to find glslang CMake targets.\")
 
         if (NOT TARGET glslang::OGLCompiler)
-            include(\"\${CMAKE_CURRENT_LIST_DIR}/../../${CMAKE_INSTALL_LIBDIR}/${PROJECT_NAME}/glslang-targets.cmake\")
+            include(\"\${CMAKE_CURRENT_LIST_DIR}/../../${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}/glslang-targets.cmake\")
         endif()
 
         add_library(OGLCompiler ALIAS glslang::OGLCompiler)
diff --git a/glslang/CMakeLists.txt b/glslang/CMakeLists.txt
--- a/glslang/CMakeLists.txt
+++ b/glslang/CMakeLists.txt
@@ -203,7 +203,7 @@ endif()
 ################################################################################
 if(ENABLE_GLSLANG_INSTALL)
     install(TARGETS glslang EXPORT glslang-targets)
-    if(NOT BUILD_SHARED_LIBS)
+    if(BUILD_SHARED_LIBS)
         install(TARGETS MachineIndependent EXPORT glslang-targets)
         install(TARGETS GenericCodeGen EXPORT glslang-targets)
 
diff --git a/glslang/OSDependent/Unix/CMakeLists.txt b/glslang/OSDependent/Unix/CMakeLists.txt
--- a/glslang/OSDependent/Unix/CMakeLists.txt
+++ b/glslang/OSDependent/Unix/CMakeLists.txt
@@ -52,7 +52,7 @@ else()
     target_link_libraries(OSDependent Threads::Threads)
 endif()
 
-if(ENABLE_GLSLANG_INSTALL AND NOT BUILD_SHARED_LIBS)
+if(ENABLE_GLSLANG_INSTALL)
     install(TARGETS OSDependent EXPORT glslang-targets)
 
     # Backward compatibility
@@ -60,7 +60,7 @@ if(ENABLE_GLSLANG_INSTALL AND NOT BUILD_SHARED_LIBS)
         message(WARNING \"Using `OSDependentTargets.cmake` is deprecated: use `find_package(glslang)` to find glslang CMake targets.\")
 
         if (NOT TARGET glslang::OSDependent)
-            include(\"\${CMAKE_CURRENT_LIST_DIR}/../../${CMAKE_INSTALL_LIBDIR}/${PROJECT_NAME}/glslang-targets.cmake\")
+            include(\"\${CMAKE_CURRENT_LIST_DIR}/../../${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}/glslang-targets.cmake\")
         endif()
 
         add_library(OSDependent ALIAS glslang::OSDependent)
